The present invention relates to an image processing apparatus and method and, more particularly, to an image processing apparatus and method for outputting input document image data to a visual image output device.
As illustrated in FIG. 13, document image data formed by DTP (Desk Top Publishing) is described in a certain kind of a PDL and converted into rasters. The raster image data is subjected to color processing by which the data is matched with the color characteristics of an output printer or an output monitor, i.e., the data is subjected to processing based on a CMM (Color Matching Method). The color-matched data is then transferred to an output unit and either printed or displayed on a monitor. In this conventional method, the color matching processing is done for all pixels by performing a color processing calculation for the raster image data in units of pixels.
Unfortunately, the above conventional method needs a long processing time for the color matching. Additionally, since the color processing calculation is done for all the pixels of the raster image data, an extremely long processing time is necessary.
Also, the color characteristics of the output printer or the output monitor differ from one apparatus to another. Therefore, when a plurality of output printers or output monitors are connected to a single host computer through a network, it is uncertain with which color characteristics the color matching is to be performed.
On the other hand, images (to be referred to as xe2x80x9cCG imagesxe2x80x9d hereinafter) formed by computers are beginning to be expressed using more colors and more gray levels. The information amount of such a multi-color image reaches about 46 Mbyte in the case of an A4-size, 400-dpi, 256-gray-level, three-color image. Therefore, such an image needs to be compressed before being stored or transmitted. In decompressing the thus compressed image and outputting the decompressed image to a device such as a printer or a display, it is necessary to perform color conversion or xcex3 conversion suitable for the output device. FIG. 14 is a view for explaining the case where compressed data is decompressed and output to a color printer.
In FIG. 14, input compressed data is converted into 8-bit R, G, and B pixel data by a decompressor 901 which includes a code analyzer 901A and a pixel data generator 901B. These 8-bit R, G, and B pixel data are converted into 8-bit C, M, Y, and K image data by color matching performed by a color processor 902 and transferred to a color printer 903. FIG. 15 is a view for explaining the processing of this color processor 902.
In FIG. 15, a LOG conversion block denoted by 2011 performs conversion from the RGB color space to the YMC color space in accordance with the following expression:
Y=xe2x88x92logB
M=xe2x88x92logGxe2x80x83xe2x80x83(1)
C=xe2x88x92logR
Subsequently, a masking block denoted by 2012 performs masking for the Y, M, and C signals, by which the signals are matched with the unique color characteristics of a printer, in accordance with the following expression:                               [                                                                      Y                  xe2x80x2                                                                                                      M                  xe2x80x2                                                                                                      C                  xe2x80x2                                                              ]                =                              [                                                                                a                    11                                                                                        a                    12                                                                                        a                    13                                                                                                                    a                    21                                                                                        a                    22                                                                                        a                    23                                                                                                                    a                    31                                                                                        a                    32                                                                                        a                    33                                                                        ]                    ⁡                      [                                                            Y                                                                              M                                                                              C                                                      ]                                              (        2        )            
In addition, a black generation block denoted by 2013 subtracts the minimum value of the Yxe2x80x2, Mxe2x80x2, and Cxe2x80x2signals, i.e., subtracts a value min(Yxe2x80x2,Mxe2x80x2,Cxe2x80x2) from the Yxe2x80x2, Mxe2x80x2, and Cxe2x80x2 signals, and replaces the subtrahend with a Kxe2x80x3 signal. This is illustrated in FIG. 16.
In this manner, the decompressed pixel data is converted pixel by pixel by using, e.g., a color conversion matrix.
It is unfortunate that the conventional method described above has the following problems.
That is, in the above conventional technique it is necessary to perform the color processing calculation for all pixel data of a decompressed image, resulting in an enormous processing time. To shorten the processing time, on the other hand, hardware capable of high-speed calculations is necessary. This raises the apparatus cost.
It is an object of the present invention to eliminate the drawbacks of the above conventional method.
That is, it is an object of the present invention to provide an image processing apparatus and method capable of outputting image information, such as a character code or a line drawing whose color is designated, to a visual image output device by efficiently and rapidly converting the image information into data which depends on the visual image output device. Also, the present invention performs color matching between a plurality of output devices during the processing.
To achieve the above object, the present invention discloses an image processing apparatus comprising supplying means for supplying image information described in a predetermined language, developing means for developing the image information into image data for each pixel, and outputting means for outputting the image data to a first output device, wherein the developing means uses a parameter which is determined based on a characteristic of the first output device and a characteristic of a second output device for developing the image information.
It is another object of the present invention to provide an image processing apparatus and method capable of efficiently and rapidly converting coded image data in units of predetermined pixel blocks into data which depends on a visual image output device.
To achieve the above object, the present invention discloses an image processing apparatus comprising supplying means for supplying image information described in a predetermined language, developing means for developing the image information into image data for each pixel, and outputting means for outputting the image data to a predetermined output device, wherein the developing means uses a parameter which is determined based on a characteristic of the predetermined output device received from the predetermined output device.
It is still another object of the present invention to provide an image processing apparatus and method capable of generating data, which depends on a visual image output device, from color images having essentially the same tone of color, without essentially performing processing for converting into the data depending on the output device.
It is still another object of the present invention to provide an image processing apparatus and method capable of reducing processing for decompressing a compressed image and outputting the decompressed image to an output device.
It is still another object of the present invention to provide an image processing apparatus and method which use a plurality of devices connected to a network and hence have a high efficiency.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.